A fluoroolefin/vinyl alcohol copolymer, i.e. a copolymer of a fluoroolefin and vinyl alcohol, is used as a raw material for coating resins, a material for gas/liquid separation membranes, a gas barrier material, a sealing material for solar cells, a material for various surface protective sheets, a hydrophilic porous material, etc. (Patent Documents 1 and 2).
As a method for producing a fluoroolefin/vinyl alcohol copolymer, a method has already been known wherein a fluoroolefin and vinyl acetate are copolymerized, followed by hydrolysis under an acidic or basic condition (Patent Documents 1 and 2, and Non-Patent Document 3). In such a method, a fluoroolefin and vinyl acetate are used as raw materials, and they are copolymerized to obtain a fluoroolefin/vinyl acetate copolymer, and in such a copolymer, an ester moiety in polymerized units based on vinyl acetate is hydrolyzed to form a hydroxy group thereby to convert the polymerized units to ones based on vinyl alcohol. However, in the method of hydrolyzing the fluoroolefin/vinyl acetate copolymer under a basic condition, although the reaction rate is high, the obtainable copolymer is likely to be colored yellow, whereby the product quality tends to be low. Whereas, in the method of hydrolyzing the fluoroolefin/vinyl acetate copolymer under an acidic condition, the reaction rate is low, and the productivity is low. Further, the obtained fluoroolefin/vinyl alcohol copolymer usually has a low thermal decomposition starting temperature and thus has a problem in thermal stability.